Ultra-violet absorbing filters



Jan. 23, 1968 F. NlTTEL ET AL ULTRA-VIOLET ABSGRBING FILTERS AbsorpfanA .n u1 9 INVENTORS 'm AroRA/Evs ULTRA-VIOLET ABSORBING FILTERS Filed Aug. 14, 1964 2 Sheets-Sheet 2 INVENTORS FRITZ N/TTEL, HANS ULRICH, HEINZ MECKL "f 3,365,295 P O Ice Patented Jan. 23, 1968 l i 2 l 3 365 295 having up to 5 carbon atoms, alkoxy preferably lower alkoxy having up to 5 carbon atoms haloUen such as ULTRA-VIOLET ABSRBING FILTERS c Fritz Nittel, Cologne, Stammheim, Hans Ulrich, Lever- Chlofme or bromme hydroxyl carboxyl mm1 and kusen, Heinz Meckl, Cologne, Flittard, and Hans-Georg ,the hke; Kleppe, Opladen, Germany, assignors to Agfa Aktien- 5 R represents hydrogen, alkyl havlng np to 18 carbon gesellschaft, Leverkusen, Germany, a corporation of atoms Preferably nP to 5 Carbon atoms snch as methyl, Germany ethyl or propyl;

Filed Ang 14, 1264, ssr-N0- 389,538 R stands for hydrogen, alkyl having up to 18 carbon Claims Priority, application Germany, SePt- 7, 1963, atoms, preferably up to 5 carbon atoms such as methyl, 7 Clairs 4(39596 84) 10 ethyl or propyl, aryl preferably :a phenyl or a naphthyl, the phenyl or naphthyl rlngs of wh1ch may be sub- This invention relates to ultra-violet absorbing filters Stitnted, for example, With alkyl, Preferably loWer alkyl for protection against the harmful effect of ultra-violet having UP to 5 carbon atoms, alloXy Preferably loWer radiation, in particular to photographic elements containalkoXy having UP to 5 carbon atoms, halogen Such aS ing the ulrrawiolet absorbing lrer, chlorine or bromine, hydroxyl, carboxyl, nitril and the It is known that certain materials are adversely effected llle; by ultra-violet radiation, when such materials are exposed X and Y each represent hydrogen, halogen such as Chlo- `to daylight. In order to protect these materials against the rlne or bromine, hydroXyl, alloXy the alkyl group of ultra-violet radiation it is common practice to provide Which has uP to 18 carbon atoms, carboXyl, carboxy1 articles of these materials with fa protective coating con- 20 esteriiied With aliphatic alcohols having np t0 18 cartaining an ultrrpviolet absorbing compound bon atoms or with benzylalcohols or cycloalkylalcohols This is especially true in the case of color photographic snch aS cyclOheXaIlol, nitril, snlfo, amino, alkyl slibimages in multilayer photographic materials Where the stitnted amino the alkyl gronp of Which has nP t0 18 dye images formed in the light-sensitive layers by color carbon atoms, aryl substituted amino in Particular Phendevelopment are susceptible to fading and discoloration ylamino, Iacyl substituted amino in Particular With thOSe by the .action of ultraviolet light to which the phoacyl groups which are derived from aliphatic carboxylic tograghic images are subjected during viewing in dayacids having UP to 20 carbon atoms, allyl having UP light. Itis advantageous to apply the ultra-violet absorpto 18 Carbon atoms Which may be substituted With Y tion compounds in separate layers since, if they are inhydroXyl and/ or alkoXy gronPs having nP to 18 carcorporated into the dye-imagecontaining layers, very 30 bon atoms Preferably 6-18 carbon atoms and carbOIlofen the opposite effect is produced, namely intensified amidefading of the dye images. It is common practice to apply the ultra-violet absorbing layer either on the unexposed The following compounds exhibit particular utility:

and unprocessed photographic material or on the processed color photographic material containing the dye I images. In particular if the absorbing layers are applied C12H25o`CH=N N- C=0 onto the unprocessed photographic element, the ultraviolet absorbing compounds have to meet certain conditions. For example, the ultra-violet absorbing compounds N=o\ /oH-CzHs must not undergo any change upon color photographic processing, should have no tendency to crystallization M'P93 C' and exudation, should have good light fasteness and should also withstand the temperatures of high glaze dry- II OmCZH ing without being damaged. r

It is an object of the present invention to provide ultra- 4" t "CH=N`N`C=O violet absorbing compounds which in particular absorb N=C CPI-02H5 light of those wave lengths which primarily cause the dye Q \S/ fading and yellowing. Another is to provide ultra-violet absorbing lter layers which in particular are applied onto M'P' 85 C' color photographs in multilayer photographic materials. Other objects will become apparent from the considera- IH C1,HO CH=N N`C=O tion of the following description and examples.

We now have found that ultra-violet absorbing compounds of the following formula can be used, in partic- Q :o oli-02H: nlar for filter coating on `color photographs to prevent dye 00 \S/ fading and discoloration and to overcome the afore- NLP-89 omentioned difficulties Without any deleterious effect of the ultra-violet absorbing compounds itself: 1V SO C9HWO* CH N N C O Wherelu t 18H31O--CIJ=NN*C=O R represents hydrogen, alkyl having up to 18 carbon atoms, preferably up to 5 carbon atoms such as methyl,

ethyl or propyl, aryl preferably a phenyl or la naphthyl, `N=C /CEPoH the phenyl or naphthyl rings of which may be sub- S M P 77o C stituted, for example, with alkyl, preferably lower alkyl The -above compounds may be prepared according to the following general method 0.1 mol of the thiosemicarbazone (A), 0.12 mol of the a-bromoalkylcarboxylic acid ethyl ester (B) and 24 g. of pyridine are dissolved in a suliicient amount of ethanol (about 100-500 ml.) and refluxed for 6 hours. Upon cooling to about 0 C. colorless crystals precipitate which are suction filtered and washed with a small amount of water and cooled ethanol. Yield: 75-90%. The product can lbe recrystallized from, for example, n-propanol.

Preparation of compound I:

50 g. of p-dodecyloxy benzaldehyde-i-phenylthiosemicarbazone,

22.3 g. of a-bromo'butyric acid ester, and

27 g. of pyridine are heated to boiling for 6 hours in 300 ml. of alcohol. On cooling, the product crystallizes out.

After rec-rystallizing twice from alcohol, 35 g. (62%) of the compound I are obtained.

The other compounds can be prepared in analogous manner. The ultra-violet absorbing compounds to be used according to the invention represent crystalline or waxy substances of good solubility and emulsifiability. The compounds are distinguished by high mo-lar extinction, good light stability and a decay of absorption at the -boundary of the visible spectral region (see the accompanying drawings). On account of their good emulsiiability, they can be introduced into the photographic layers in the form of emulsions without any ditiiculty. For the preparation of the emulsions, it is possible also to use high-boiling organic solvents, such as phosphoric acid esters or esters `of polybasic carboxylic acids such as phthalic or adipic acid.

The use of the compounds is not restricted to color photographic purposes; it can also be extended to any desired other elds of use, such as plastic foils, light iilters and packing materials.

The application to photographic elements is shown in the following examples:

Example 1 760 ml. of aqueous gelatin solution and 40 ml. of a 10% aqueous solution of dodecyl benzene sulfonate as emulsier are vigorously stirred in an emulsifying apparatus and a solution consisting of 20 g. of the compound XIII dissolved in 50 rnl. of ethyl acetate, is slowely added. The mixture is stirred for -20 minutes. After cooling, the solidied mass is formed into noodles and dried. The dried emulsion is completely clear. It is applied as a 2-5% aqueous solution as a protective layer onto a light-sensitive multilayer color photographic material. Layer thickness: 1-5 microns.

A solution suitable for casting can also be prepared by diluting the 10% emulsion to a 2-5% solution instead of drying it. Alternatively, in the emulsifying operation a 2-5% gelatin solution may be used.

The example can be modified in such a way that up to 50% of the weight of gelatin is replaced by the ultraviolet absorbing compound.

After usual color-forming processing of the photographic material, images are obtained in which the light fastness is improved by a factor of 2-10, depending on the layer thickness and concentration of the ultra-violet absorbing compound.

The improvement in the fastness is determined by an image with an ultra-violet protective layer and an image with a pure gelatin protective layer being exposed until the same degree of fading is reached. The ratio of the lux hours required gives the improvement factor.

Example 2 To illustrate the stability of the compounds of the present invention to ultra-violet light and to show the absorption characteristics of the compounds, the following tests were made:

(l) An ultra-violet absorbing lilter layer on a transparent cellulose acetate support is produced as described in Example 1. The dried layer contained 2% by weight of the ultra-violet absorbing compounds and had a thickness of 5 microns.

The absorption of the above ultra-violet absorbing iilter was measured without prior exposure and again after exposure with an incandescent lamp (2.5 -106 lux hours). The results are given in FIG. 1. Curve 1 represents the absorption without prior exposure and curve 2 the absorption after the exposure, The test shows that the compound is not decomposed and the absorption not decreased by the exposure.

(2) The absorption of an ethyl acetate solution of -compound I containing 1 part of the compound in 250,000 parts of a solvent (curve 3 in FIG. 2) and another ethyl acetate solution containing one part of the compound in 1,000 parts of the solvent (curve 4 in FIG. 2) is measured.

The results are given in FIG. 2. The absorption curves show the sharp decay of the absorption towards longer wavelength.

Example 3 ml. of 10% aqueous gelatin solution and 10 ml. of a 10% aqueous s-olution of saponine as emulsiiier are mixed in the manner referred to in Example 1 with 2 g. of the compound V dissolved in 25 ml. of ethyl acetate, and further processed as in Example l.

The ultra-violet absorber layers obtained in accordance with the above examples are completely clear, withstand the col-or processing without any change and do not show any exudation phenomena under high glaze drying. No precipitation occurs during the storage of the aqueous heated emulsions.

Example 4 .s

100 ml. of 10% aqueous gelatin solution and 10 ml. of a 10% aqueous solution of saponine as emulsiiier are mixed in the manner referred to in Example 1 with 2 g. of the compound XIX dissolved in 15 ml. of ethyl acetate, and further processed as in Example l.

The ultra-violet absorber layers obtained are completely clear, withstand the color processing without any change and do not show any exudation phenomena under high glaze drying. No precipitation occurs during the storage of the aqueous heated emulsions.

Example 5 A color photographic image in a processed multilayer film or paper strip is coated with an ultra-violet absorbing layer as Idescribed in Example 1. Measuring of the coated element indicates a considerable density to ultra-violet light. The light fastness of the color photograph is improved by the factor 10 as compared with a color photograph of the same type without a protective layer. The thickness of the layer is about 3 microns.

If applied in the form of a protective layer, the thickness of the ultra-violet absorbing layer is preferably between l and 10 microns, more preferably between 1 and 5 microns. The layer may contain between 5 and 50% by weight of the ultra-Violet absorbing compounds based on the weight of the dried layer.

We claim:

1. A photographic element comprising at least one supported photographic silver halide emulsion layer and a layer containing an effective amount of an ultra-violet absorbing compound of the following formula:

wherein R and R each represent a member of the group consisting of hydrogen, alkyl having up to 18 carbon atoms, and aryl;

R stands for a member of the group consisting of hydrogen and alkyl having up to i8 carbon atoms, and

X and Y each represent a member of the group consisting of hydrogen, halogen, hydroxyl, alkoxy the alkyl of which has up to 18 carbon atoms, carboxyl, esteried carboxyl. carbonamide, nitril, sulfo, amino, alkyl substituted amino, aryl substituted amino, acyl substituted amino, alkyl having up to 1S carbon atoms, hydroxy substituted alkyl and alkoxy substituted alkyl.

2. A photographic element as defined in claim 1, wherein R is alkyl having up to 5 carbon atoms, R is phenyl and R is hydrogen.

3. A supported ultra-violet absorbing filter layer containing an effective amount of an ultra-violet absorbing compound of the following formula:

wherein I?. and R each represent a member of the group consisting of hydrogen, alkyl having up to 18 carbon atoms, and aryl;

R stands for a member of the group consisting of hydrogen and alkyl having up to 1S carbon atoms.. and

X and Y each represent a member of the group consisting of hydrogen, halogen, hydroxyl, alkoxy the alkyl of which has up to 18 carbon atoms, carboxyl, estenl ied carboxyl, carbonamide, nitril, sulfo, amino,

Cil

alkyl substituted amino, aryl substituted amino, acyl substituted amino, alkyl having up to 18 carbon atoms, hydroxy substituted alkyl and alkoxy substituted alkyl. is. A supported ultra-violet absorbing lter layer as defined in claim 3, wherein P. is alkyl having up to 5 carbon atoms, R" is phenyl, and R is hydrogen.

5. A finished color photographic element comprising a support having thereon a plurality of processed photographic emulsion layers Containing coupled-dye images at least one of said dye images being subject to fading by the action of ultra-violet radiation, the layer containing said image being arranged between said support and a protective layer containing an effective amount of an ultraviolet absorbing compound of the following formula wherein R and R" each represent a member of the group consisting of hydrogen, alkyl having up to 18 carbon atoms, and aryl;

R stands for a member of the group consisting of hydrogen and alkyl having up to 1S carbon atoms, and

X and Y each represent a member of the group Consisting of hydrogen, halogen, hydroxyl, alkoxy the alkyl of which has up to 18 carbon atoms, carboxyl, csteried carboxyl, carbonamide, nitril, sulfo, amino, alkyl substituted amino, aryl substituted amino, acyl substituted amino, alkyl having up to 18 carbon atoms, hydroxy substituted alkyl and alkoxy substituted alkyl.

6. A finished color photographic element as defined in claim S, wherein R is alkyl having up to 5 carbon atoms, R is phenyl, and l?. is hydrogen.

7. A nished color photographic element as defined in claim 5, wherein the support is a paper support.

References Cited UNlTED STATES PATENTS 2,798,067 7/1957 Sav/dey 96-84 NORMAN G. TORCHIN, Primary Examiner.

R. H. SMITH, Assistant Examinez'. 

1. A PHOTOGRAPHIC ELEMENT COMPRISING AT LEAST ONE SUPPORTED PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER AND A LAYER CONTAINING AN EFFECTIVE AMOUNT OF AN ULTRA-VIOLET ABSORBING COMPOUND OF THE FOLLOWING FORMULA:
 3. A SUPPORTED ULTRA-VIOLET ABSORBING FILTER LAYER CONTAINING AN EFFECTIVE AMOUNT OF AN ULTRA-VIOLET ABSORBING COMPOUND OF THE FOLLOWING FORMULA: 